JP5243270B2 - EL device with improved power distribution - Google Patents

Description

  The present invention relates to electroluminescent devices and, more particularly, to electroluminescent device structures for improving power distribution.

  Coated electroluminescent (EL) devices are a promising technology for flat-panel displays and area illumination lamps. Advances in EL devices, especially in the organic light-emitting diode (OLED) subclass, make this technology competing with traditional LCD technology for display and tungsten or fluorescent lamps for area lighting. is there. This technique relies on thin film layers made of various materials covering the substrate. For OLED devices, the material is an organic material, but EL devices can also be formed from an inorganic layer or a combination of organic and inorganic layers.

  OLED devices are commonly known as small molecule devices (such as those disclosed in US Pat. No. 4,476,292) and those known as polymer OLED devices (such as those disclosed in US Pat. No. 5,247,190). Two forms are possible. Both types of OLED devices can in turn include an anode, an organic EL element, and a cathode. In most designs, one electrode is reflective and the other electrode is transparent. An organic EL device disposed between an anode and a cathode generally includes an organic hole transport layer (HTL), a light emitting layer (EL), and an organic electron transport layer (ETL). Recombines with EL to generate light. Tang et al. (Appl. Phys. Lett., 51, 913, 1987; Journal of Applied Physics, 65, 3610, 1989; US Pat. No. 4,769,292) uses such a layer structure. Made a high-efficiency OLED. Since then, numerous OLEDs with different layer structures containing polymeric materials have been disclosed and device performance has been improved.

  In OLED devices, when electrons and holes are injected from the cathode and anode respectively, they flow through the electron transport layer (ETL) and hole transport layer (HTL) and recombine in the light emitting layer (LEL). Light is generated. Many factors determine the efficiency of this light generation process. For example, the choice of anode and cathode materials can determine how efficiently electrons and holes are injected into the device. The choice of ETL and HTL can determine how efficiently electrons and holes are transported through the device, and the choice of LEL allows the electrons and holes to recombine efficiently to produce light. You can decide what happens.

  A typical OLED device uses a glass substrate, a transparent conductive anode (eg, indium-tin-oxide (ITO)), a plurality of stacked organic layers, and a reflective cathode layer. The light generated from this device exits through the glass substrate. This is commonly called a bottom-emission device. Alternatively, the device can comprise a substrate, a reflective anode, a plurality of stacked organic layers, a transparent upper cathode layer, and a transparent cover. Light generated from this device exits through a transparent upper cathode layer and a transparent cover. This is commonly referred to as a top-emission device.

  In OLED devices, various organic light emitting materials that are patterned on a substrate and emit light of different wavelengths (eg, red, green, blue) can be used to produce a full-color display. Alternatively, white light is generated using a combination of multiple light emitters or a single broadband emitter that is not patterned, and different colors are used using patterned color filters (eg, red, green, blue) together It is known to produce light-emitting elements and full-color displays. The color filter can be placed on the substrate (bottom-emission type) or on the cover (top-emission type). Such a device is described, for example, in US Pat. No. 6,392,340 entitled “Color Display Device with Electroluminescent Elements” granted May 21, 2002.

  OLED materials have various emission characteristics. Furthermore, it is known that light of one color has a higher luminous efficiency than light of another color. In particular, it is known that white light emitters are more efficient than blue light emitters and red light emitters. Thus, it has been proposed to use OLED pixels with four sub-elements, namely red, green, blue and white (RGBW). Because most images have a large luminance component, such a four-element display can be more efficient than a traditional three-element display. Such a design is described, for example, in US Pat. No. 6,919,681 and US Patent Application Publication No. 2004/0113875. Since white light emitters are more efficient than color light emitters, replacing some of the light generated by the combination of a plurality of color light emitters with white light emitters may reduce the power used. Further, as described in U.S. Patent Application Publication No. 2004/0178974, even if a fourth color gamut determining color light emitting element having a power efficiency higher than at least one of the RGB light emitting elements is applied, the display efficiency is improved. Can be improved.

  Referring to FIG. 3, a side view of a bottom-emission type OLED device proposed in the prior art with a transparent substrate 50 is shown. A semiconductive layer is formed on the substrate 50 to form the thin film electronic component 24 for driving the OLED. An insulating / planarizing intermediate layer 40 is formed on the thin film electronic component 24, and a patterned transparent electrode 52 that defines a light emitting element of the OLED is formed between the insulating layer 40 and the insulating layer 40. . An inter-light-emitting element insulating film 42 separates various elements from the patterned transparent electrode 52. One or more first organic material layers 54 (one of which emits light) are formed on the patterned transparent electrode 52. A reflective second electrode 56 is formed on one or more first layers 54 made of an organic material. In some conventional embodiments, the patterned transparent electrode 52 can instead be at least partially transparent and / or light absorbing.

  As shown in the RGBW arrangement of FIG. 3, the organic layer 54 does not need to be patterned, and broadband light (eg, white light) exits the organic layer 54 through the color filters 44R, 44G, and 44B. -Form the display. Color filters 44R, 44G, 44B only transmit light of the desired color (eg, red, green, blue corresponding to the color desired in the color display), whereas filter 44K is a neutral filter (or filter A transparent layer may be present without). Next, colored light 60, 61, 62 and broadband light or white light 63 pass through the substrate 50 and exit the device. Alternatively, the organic layer 54 is patterned so that different colors of light exit from different locations on the device. At that time, the filters 44R, 44G, and 44B need not be used. Applicant has configured an OLED device corresponding to FIG.

  Unlike other flat-panel display devices, active matrix OLED devices that use thin film electronic components to drive OLED elements generally have problems with power distribution within the OLED device. Since OLED devices generate light directly and their light output depends on the current passing through the OLED, it is important that sufficient and uniform current is available in each OLED included in the active matrix OLED device.

  In an OLED device, conventionally, a plurality of pixels are arranged in a plurality of rows and columns, and a bus column or a bus row supplies power to each OLED pixel. Therefore, each pixel column (or pixel row) shares a common bus (and other signals (such as a data signal and a selection signal)). This configuration is used to simplify the pixel layout and maximize the resolution of the OLED device. In the active-matrix OLED, a thin film transistor circuit for adjusting a current supplied to each OLED in the display device is provided. However, current is typically supplied to a number of pixels in a row or column by a power line and return pair. Because these lines have finite resistance values, as the current required to drive each OLED element increases, an unexpected and undesirable voltage difference results in the flowing current and the resistance values of the power and return lines. Occurs as a function of Because this unexpected voltage difference is positively correlated with current and resistance values, voltage drops along the power lines and / or return lines can cause large currents to flow or when the power line resistance is high. growing. This phenomenon of generating an unexpected voltage difference is generally referred to as current-resistance drop, or “IR” drop. Furthermore, due to this IR reduction, the luminance of the pixels is gradually lost along the power line as the distance from the power source increases. This reduction in brightness can cause undesirable artifacts in imaging. Therefore, it is necessary to limit unexpected voltage drops to avoid such artifacts. Referring to FIGS. 6A and 6B, diagrams are provided showing the actual artifacts of images observed with commercially available active-matrix OLEDs. Area 1 is brightly shining, so a large amount of power is being supplied. Because the common signal emits less light from region 2 including part 2a, and region 2 is farther from the power supply than region 1, the current is for the column found in this active-matrix OLED for illustration. You have to pass longer distances in the bus. Part 2a is driven with the same signal used to drive the rest of region 2, but the current in part 2a is limited by the current flowing along the column bus in region 1 unlike the other parts Therefore, the luminance is smaller than that of the remaining area 2. As a result, unexpected and undesirable artifacts are observed in the image. In particular, the artifact is a columnar structure and is defined by the power line and return line layout within the display device.

  One way to overcome this problem is to reduce the resistance of the power line, as suggested in US Patent Application Publication 2004/000444, entitled “Light Emitting Panel and Light Emitting Device With It”. The bath is typically composed of aluminum, or silver, or other metal, or alloy, and can be, for example, 10 microns wide and 250 nm thick. Unfortunately, the materials that can be used to reduce resistance and power line cross-section (inversely proportional to resistance) depend on the available manufacturing technology, so costly to reduce power line resistance. Often not effective. Because the resistance increases as the power line becomes longer, and the peak brightness of the display is limited by the peak current that can be supplied along the power line, the size or brightness of the display that can be manufactured using OLED technology is limited. There is often.

  Another method in the prior art to address this problem is based on increasing the size of the power distribution bus and sacrificing other display elements. For example, if the size (opening ratio) of the light emitting region of the OLED is reduced, the size of the bus can be increased (and the bus conductivity is improved). However, this will shorten the lifetime of the OLED device. It is known that the current density through the OLED material increases (if the brightness is a given value), and that the lifetime of the OLED device is inversely related to the current density through the OLED. That is why. Referring to FIG. 4A, a top view of a conventional OLED layout is shown. The OLED includes two adjacent pixels 10a and 10b having light emitting regions 20a and 20b, thin film electronic components (TFT) 24a and 24b, and buses 14a and 14b. Due to limitations in the manufacturing method, the accuracy with which various parts are placed is limited. It is therefore necessary to provide space 8 between the various elements of the device. A variety of layout design rules and layers are known in the prior art, which determines the space 8 to be considered for the various elements of the device. The drawings shown here are very simple and rough. Note especially the space 8 associated with the bus 14. Two spaces 8 are provided in each pixel 10. U.S. Pat. No. 6,522,079 describes an OLED layout with improved bus width without reducing the aperture ratio. Referring to FIG. 4B, by reducing the number of buses, the number of spaces 8 between any two pixels can be reduced to three. Additional space 14 'can be used to increase the size of the remaining bus (as shown) to improve conductivity and power distribution, or for other purposes (e.g., increasing aperture ratio, It can be used to extend the lifetime of OLED devices). US Pat. No. 6,771,028 describes a drive circuit for a four color organic light emitting device and includes a similar inversion layout embodiment in which adjacent light emitting element arrays share a common bus. . Although such a layout allows this increase in size and conductivity, power distribution remains a major problem and further improvements would be desirable.

  Reference is now made to FIG. 4C. Another method for improving the power distribution of an OLED device using a bus for rows or columns is described in US Pat. No. 6,724,149. In this design, bypass-type interconnections 12a and 12b that electrically connect the buses 14 are used so that current can reach from one bus to another. However, if such interconnections are used between each light emitting element row, the aperture ratio of the OLED device can be significantly reduced, especially in bottom-emission OLED configurations.

  Every active-matrix EL device presents a similar problem because all EL devices, including OLED devices, generate light in response to current passing through the device. Therefore, there is a need to improve the EL device layout to eliminate the problems noted above and to provide more area for power bus lines and / or light emitting areas while reducing visible artifacts. .

One embodiment of the present invention includes a plurality of light-emitting elements laid out on a substrate (where each light-emitting element includes a first electrode, a second electrode, and one or more electrodes formed between the electrodes). A luminescent layer, wherein at least one electroluminescent layer emits light, at least one electrode is transparent, and the first electrode and the second electrode define one or more light-emitting regions), An electronic component formed on the substrate and connected to the first electrode and / or the second electrode to drive one or more electroluminescent layers to generate light;
A plurality of buses connected to the light emitting elements for transmitting a common signal;
An active-matrix electroluminescent device comprising a plurality of electrical interconnects that intersect the plurality of buses and electrically connect the plurality of buses;
The plurality of light-emitting elements are arranged as a plurality of groups of four light-emitting elements, and each group includes four adjacent light-emitting elements arranged around the intersection of the bus and the electrical interconnection part. 4 light emitting elements are formed on each side of one bus, and 4 light emitting elements are formed on each side of one electrical interconnect. Two light emitting elements of the cell are formed;
Each light emitting element of each quadruple cell is connected to a bus or electrical interconnect that separates the light emitting elements of the quadruple cell from each other, and each quadruple cell is connected to an adjacent quadruple cell. Adjacent quaternary cells that share a common bus or electrical interconnect and share a common bus are not separated by a common interconnect, Shared adjacent quadruple cells are for active matrix devices that are not separated by a common bus.

  The present invention has the advantage of improving the power distribution and emission uniformity of active-matrix electroluminescent devices.

  It will be understood that the drawings are not in actual scale because the differences in size of the individual elements are so large that they cannot be represented in actual scale.

  Referring to FIG. 1 according to one embodiment of the present invention, an active-matrix electroluminescent device comprises a plurality of light emitting elements 10a, 10b, 10c, 10d disposed on a substrate. Referring to FIG. 3, the light emitting elements can be similarly formed on the substrate 50, and each OLED element has a first electrode 52, a second electrode 56, and a 1 formed between these electrodes. One or more electroluminescent layers 54 are provided. At least one electroluminescent layer 54 emits light, and at least one of the electrodes 52 and 56 is transparent, and the electrodes 52 and 56 define one or more light emitting regions. In FIG. 1, the light emitting elements 10a, 10b, 10c, and 10d further include light emitting regions 20a, 20b, 20c, and 20d formed on the substrate 50 and electronic components 24a, 24b, 24c, and 24d. Is shown. The light emitting region and the electronic component are connected to the first electrode 52 and / or the second electrode 56 to drive one or more electroluminescent layers 54 to generate light.

  A plurality of buses 14a and 14b for transmitting a common signal are connected to the light emitting element. Further, the plurality of electrical interconnection portions 12a and 12b intersect to electrically connect the plurality of buses. The plurality of light emitting elements are arranged in a plurality of groups each consisting of four light emitting elements (10a, 10b, 10c, 10d), and each group is arranged adjacent to the intersection of the bus and the interconnection part. A quadruple cell (4a, 4b, 4c, 4d) composed of four matching light emitting elements is formed. Two light emitting elements of each quadruple cell are formed on each side of the bus (for example, in quadruple cell 4a, pairs 10a and 10c and pairs 10b and 10d are formed on opposite sides of bus 14a) , Two OLED elements are formed on each side of each quadruple cell electrical interconnect (for example, in quadruple cell 4a, pair 10a, 10b and pair 10c, 10d are electrical interconnect Formed on opposite sides of 12a). Each light emitting element of each quadruple cell is connected to a bus or electrical interconnect that separates the light emitting elements of the quadruple cell from each other, and each quadruple cell is adjacent to the quadruple cell (For example, a quadruple cell 4a shares a common bus 14a with an adjacent quadruple cell 4c and a common electrical cell with an adjacent quadruple cell 4b). Share interconnect 12a). Adjacent quadruple cells sharing a common bus are not separated from each other by a common interconnect, and adjacent quadruple cells sharing a common interconnect are separated from each other by a common bus. Not. This arrangement forms a group of four light emitting elements located in four sections formed by the intersection of the buses 14a, 14b and the electrical interconnections 12a, 12b. This arrangement according to the invention of the light emitting elements, buses, electrical interconnections makes it possible to optimize the combination of the power distribution and the aperture ratio of the light emitting elements. In one embodiment, the electroluminescent layer contains organic electroluminescent materials including organic light emitting diodes, so these light emitting elements can be referred to as OLED elements.

  Further, from FIG. 1, the light emitting elements (10a, 10c) on one side of the bus 14a can be an inverted layout of the light emitting elements (10b, 10d) on the other side of the bus 14a, so that It can be seen that the light emitting elements (10a, 10b) on one side of the connection part 12a can be an inverted layout of the light emitting elements (10c, 10d) on the other side of the electrical interconnection part 12a. As used in the present invention, the inversion layout is a layout in which the positions of the light emitting region 20 and the electronic component 24 in each light emitting element 10 are almost reversed with respect to the bus 14 and the electrical interconnect 12. Means. The inverted layout can be a mirror image. In that case, the position of each component included in the light emitting element 10 is in the position of the mirror image of the corresponding component in another light emitting element 10. However, according to the present invention, a strict mirror image is not required, and the light emitting regions may be different from each other as shown in FIG. Furthermore, the connection part of the electronic component 24 included in each light emitting element 10 and the bus 14 and / or the electrical interconnection part 12 can be arranged at various positions. For example, referring to FIG. 2, a connection 22 can be formed between the electronic component 24 included in one light emitting element 10 and the bus 14 through the via 16 at one position of one light emitting element 10, but another light emission It can be seen that element 10 can be connected to the same bus or interconnect 12 through a via at an inverted or different position to form a connection 22. Since the bus 14 and the interconnect 12 are electrically connected, the electrical circuits formed by the connections 22 are substantially the same, and other examples of such locations are included in the present invention. Further, according to the present invention, the electronic component 24 can be configured not to have an inversion layout, but it is preferable to use the inversion layout to simplify the connection to the light emitting area 20, the bus 14, and the interconnect 12. Let's go. In addition, the inverted layout allows all the light emitting elements of the quadruple cell to be located closer to the intersection of the bus and electrical interconnects than the edge of the quadruple cell. It becomes easy to connect to the interconnection. This improves the uniformity of the current distribution to the individual elements of the quadruple cell, thus increasing the uniformity of light emission.

  In general, since the light emitting element 10 can have a linear layout that forms a plurality of orthogonal rows and columns, the electrical interconnect 12 is formed at the position of the first common edge of the light emitting element 10, and the bus 14 is formed at the second common edge of the light emitting element 10 orthogonal to the first common edge. The bus 14 and / or the electrical interconnect 12 can carry a power signal or a ground signal shared among all the light emitting elements 10. In various embodiments of the present invention, the bus 14 and the interconnect 12 can be formed in one common layer (as shown in FIG. 1) in one common step and made of the same material (eg, aluminum , Metals such as silver and magnesium, and alloys thereof. Alternatively, as shown in FIG. 2, the bus 14 and interconnect 12 can be formed in separate layers in separate steps and can be electrically connected through connecting vias 16 at the intersections.

  The present invention can be used in either a top-emission type configuration or a bottom-emission type configuration. However, since the layout is limited in the bottom-emission type configuration, it is advantageous to use the present invention in the bottom-emission type configuration.

  The present invention is superior to the prior art because it improves layout efficiency by improving layout efficiency. Both electrical interconnect 12 and bus 14 simultaneously carry a common signal applied to two or more rows or columns, so they are electrically connected and manufacturing spacing is made using an inverted layout. It would be good to reduce the tolerance of the display area, thereby increasing the area available in the display device. Take advantage of this area to increase the conductivity of the shared electrical interconnect 12 and bus 14, or increase the aperture ratio of the display, or provide more area for more sophisticated electronic components 24 be able to. In the example of FIG. 1, the width of the shared electrical interconnect 12 and the bus 14 can be increased by 25% while maintaining the same aperture ratio as compared to the case of using two separate buses. If the electrical interconnect 12 and the bus 14 carry a large current signal (eg connection to power or ground), the multi-directional (eg orthogonal) connection will enhance the current in the area where local demands are present. Provide transmission ability. In this case, if the light emitting device 10 requires more current than can be provided through a single bus 14, it will provide additional current from the nearby bus 14 through the electrical interconnect 12 close to the light emitting device 10. This can improve the uniformity of the light output from the electroluminescent device. With this improved power distribution, undesirable edge effects seen in the display can be reduced. For example, a low frequency can tolerate 30% uniformity across the display, but at a high frequency, the demand for uniformity at the boundary between high and low brightness is much more demanding (see Figure 6A and Figure 6). For example, less than 5% (as shown in 6B).

  It should be noted that the present invention can be successfully used in any layout where four adjacent light emitting elements share a common power line and that power line is connected to at least one adjacent power line. As an example of 4-element arrangement, three of the elements are composed of red, green, and blue light-emitting elements, and the fourth light-emitting element is either green, yellow, cyan, magenta, or white It is possible to emit light. Alternatively, the four adjacent elements can be composed of two pairs of complementary colors. In this case, the two complementary pairs are selected from a pair of red / cyan light emitting elements, green / magenta light emitting elements, and blue / yellow light emitting elements. Further, a configuration in which a plurality of quadruple patterns are adjacent to each other is not necessarily configured with light emitting elements that emit light of the same color. Instead, for example, one quadruple includes a light emitting element that emits red, green, blue, and white light, while the adjacent quadruple includes red, green, cyan, and white light. It is possible to have a configuration including an OLED that emits light.

  The present invention is particularly useful when forming a full-color display system comprising an active-matrix electroluminescent display device, regardless of the color of the light emitting element used. However, the display device includes a plurality of light-emitting elements laid out on a substrate (where each light-emitting element includes a first electrode, a second electrode, and one or more electroluminescent layers formed between the electrodes). And at least one electroluminescent layer emits light, the first electrode and the second electrode define one or more light emitting regions, and at least one electrode is transparent); and formed on a substrate An electronic component connected to the first electrode and / or the second electrode to drive one or more electroluminescent layers to generate light; connected to the light emitting element and common It has two or more buses that carry signals. In this full-color display system, the active-matrix electroluminescent display device has four or more colors of light emitting elements, and each of the two or more buses emits light of four or more colors. A current is provided to a pixel having a group of light-emitting elements including. In this full-color display system, the display device is driven by a controller that controls the pixels and limits the current provided to the light emitting devices of four or more colors, so that all four light emitting devices are used simultaneously. When the light intensity of at least one light emitting element is approximately the same as the color of the light emitting element, the light intensity of at least one light emitting element is set to be lower than the peak light intensity of the same light emitting element. Thus, the current provided by each bus is less than the sum of the individual design peak currents for each light emitting device. This system is even more advantageous when the electroluminescent display further comprises an electrical interconnect that electrically connects at least two buses to better distribute power. This is when the light emitting element on one side of the part has a light emitting element with an inverted layout on the other side of the electrical interconnect.

  In such a display system, when all four light emitting elements are used at the same time by controlling the pixels using a control device and limiting the current supplied to the light emitting elements of four colors or more, at least 1 When the light intensity of one light emitting element is substantially the same as the color of the light emitting element, the light intensity can be made lower than the peak light intensity of the same light emitting element. In such an embodiment, two or more buses connected to the light emitting elements and carrying a common signal need to provide sufficient current to provide peak current for all light emitting elements of four or more colors. Absent. Therefore, the total area of the power line and the return line required to achieve the predetermined maximum IR reduction is required when all the light emitting elements of four or more different colors do not share the common power line and the return line. It will be smaller than the total area of the power line and return line. Furthermore, when two light emitting elements are formed on each side of a power line and a return line, no space is required between adjacent elements across the two power lines and the return line, but a single power line and return line and its return Space between elements next to the line is necessary. After all, when two OLED elements are formed on each side of an interconnect, only space is required between one interconnect and the adjacent element. Therefore, a display system having such a feature is advantageous over the prior art in that the power distribution is improved as the layout efficiency increases.

  A portion 78 of such a display is shown in FIG. As can be seen from this figure, the display portion 78 includes light emitting elements of four different colors. Among them, a green light emitting element 80, a red light emitting element 82, a blue light emitting element 84, and a white light emitting element 86 are included. A power line 88 is shown supplying power to all four light emitting elements. The electrical interconnect 90 also divides the four light emitting elements, and the effect is shared by these four different color light emitting elements. Although the power line and the interconnect are shared, select lines 92a and 92b are provided in each pixel column. Furthermore, capacitor lines 94a and 94b and drive lines 96a and 96b are provided in each light emitting element row in the display device.

  Desirably, a power line 88 and select lines (92a and 92b) are provided in the first metallization layer in the display device. As shown, capacitor lines 94a, 94b, drive lines 96a, 96b, and electrical interconnect 90 may be provided in a second metallization layer separated from the first metallization layer by a dielectric layer. it can. Alternatively, the electrical interconnect can be formed in a separate layer (eg, an ITO layer that forms the anode of a bottom-emission active-matrix electroluminescent device). Note that the first metallization layer and the second metallization layer can be interconnected by vias (eg, via 98 connecting electrical interconnect 90 to power line 88).

  As already pointed out, the power line 88 is shared between the two light emitting element columns, and the fact that the electrical interconnect 90 is shared between the two light emitting element rows is assigned to these two elements. The area on the substrate is reduced, and more importantly, the area allocated between these elements and neighboring structures in the electroluminescent device is reduced.

  It should also be noted that a group of light emitting elements forming a quadruple cell can be tiled across the display substrate, but this is not necessary. In FIG. 8, four quadruple cells 110, 112, 114, 116 are shown as part of an electroluminescent display device. As can be seen from this figure, the quadruple cells 110 and 114 are supplied with power from the power line 88a, while the quadruple cells 112 and 116 are supplied with power from the power line 88b. The electrical interconnect 90a has the function of connecting the power lines 88a and 88b between the quadruple cells 110 and 112, whereas the electrical interconnect 90b is between the quadruple cells 114 and 116. It has a function of connecting the power lines 88a and 88b. However, there may be differences between these quadruple cells. In fact, the quadruple cells 110 and 114 can be formed from two upper light emitting elements that generate green light and red light, and two lower light emitting elements that generate blue light and white light. On the other hand, the quadruple cells 112 and 116 are composed of four light emitting elements configured as two upper light emitting elements that generate blue light and white light and two lower light emitting elements that generate green light and red light. Can be formed. Note also that quadruple cells can be square in shape (ie, the vertical size of the quadruple cell is equal to the horizontal size), but can also be rectangular. In fact, in some implementations (especially when the quadruple cell horizontal or vertical size is twice the size of the other direction) it may be desirable to have a rectangular quadruple cell. . In such an embodiment, for example, a pair of two light emitting elements in each quadruple cell can be combined into a substantially square shape.

  As already pointed out, such a display device uses four or more colors of OLEDs and a control device that controls the pixels and limits the current supplied to the light emitting elements of the four or more colors. When all of the elements are used at the same time, the light intensity of at least one light emitting element is less than the peak light intensity of the same light emitting element if the color of the displayed light is approximately the same as the color of the light emitting element It is preferable to do so. Therefore, the current provided by each bus is smaller than the sum of peak currents required for driving each light emitting element. When all four light emitting elements are used simultaneously, if the light intensity of at least one light emitting element is approximately the same as the color of the light emitting element, the peak light intensity of the same light emitting element Preferably no more than half. The current provided by each bus is then significantly smaller than the sum of the peak currents required to drive each light emitting element, resulting in a significantly smaller size required for the power line. This control device can convert a three-color input signal into a signal of four colors or more, and if it can perform color conversion so as not to simultaneously reach the individual design peak currents of the four OLEDs, Any of a digital processor, an analog processor, and a hybrid processor may be used. With such a device, a color conversion algorithm can be used to convert a three-color input signal into a signal of four or more colors. Several such color conversion algorithms are known in the prior art, for example, U.S. Pat. No. 6,897,876 entitled "Method for Converting a Three-Color Input Signal to an Output Signal More Than Four Colors for a Color Display". , United States Patent No. 6,885,380 entitled “Method of Converting Three Color Input Signals to Four or More Color Output Signals for Color Display”, United States Patent Application Named “Color OLED Display with Improved Power Efficiency” Those described in the publication 2005/0212728 are mentioned (the contents of these patent documents are assumed to be included in this specification for reference). Referring to the display device shown in FIG. 8 again, such color conversion can be performed using the color conversion process shown in FIG.

  As shown in FIG. 9, an RGB signal is input 120 and converted to RGB linear intensity 122 using a conventionally known method. Conventional methods often require linearization of input RGB signal values. This input RGB signal value is generally coded in log space and may require color rotation to rotate from the coded color space to the color space defined by the primary colors of the display. When the numerical value is expressed as a linear intensity value, the minimum intensity values for red, green, and blue can be determined 124. Next, a portion of this minimum value is subtracted 126 from each of the red, green and blue channels 126. The white channel value is then calculated 128 using a portion of this same minimum value. This value is generally formed as part of this minimum intensity value. Subtracting some of the minimum RGB intensity values (greater than 0) from the red, green, and blue channels, and forming further white channels from this same minimum value is the peak value of the red, green, and blue channels Note that is surely smaller than the peak value when displaying fully saturated primary colors of red, green and blue. Therefore, using this method, color conversion is performed such that the individual design peak values of the four light emitting elements are not reached simultaneously. The resulting red, green, blue and white signal values are then rendered 130 and sent to the display. In OLED display devices, this rendering process often includes a linear intensity-to-voltage look-up table that compensates for the non-linear response of the OLED to the voltage input.

  As shown in this detailed embodiment, the present invention may be useful in combination when designing pixels for RGBW OLED displays using red, green, blue and white light emitting elements. As known in the prior art, an OLED utilizing RGBW design by using white light emitting elements instead of combining color light emitting elements to reduce the power required to form any unsaturated color The total power consumed by the display can be reduced. The device configured as described above generates broadband light from the light emitting layer in the light emitting element, and filters at least part of this light using a color filter to provide a red light emitting element, a green light emitting element, and a blue light emitting element. It is known to be especially helpful when you do. As described above, the control device can be used to control the four color light emitting elements so that all four light emitting elements are not turned on at maximum brightness at the same time. If these four subpixels are then placed on the shared bus 14 and the interconnect 12, the peak current required for the single bus 14 and interconnect 12 can be significantly reduced. This reduces the design peak current required for the display and improves the current distribution and light output uniformity in this device. For example, in a general device, it is necessary to drive a red light emitting element, a green light emitting element, and a blue light emitting element with a peak current of 20 mA. White can be obtained by using this value of current, but the same white can be obtained by driving a white light emitting element at 8 mA. If white is formed using only RGB elements, the display will need to supply 60mA to each quadruple cell (20mA for each color light-emitting element). On the other hand, when the color conversion according to the present invention is applied so that half of the light is generated by the color light emitting element and the other half is generated by the white light emitting element (ie, the subtracted portion 126 and the portion 128 used for calculation). 0.5), and each of the quadruple cells will only need 34mA (half the sum of the peak currents of the red, green, blue and white light emitting elements). Furthermore, using the color conversion shown above, the portion 126 subtracted from the minimum value is greater than 0 and less than or equal to 1, and the portion 128 of the minimum value used for calculation is subtracted from the minimum value. The peak current will occur when an isochromatic color is formed by combining the peak currents for the two color elements (ie, a value of 40 mA). . Note that the same white color can be generated using other known color change algorithms that effectively add the white luminance to the RGB luminance. In this example, a brighter color will occur, but the display will need to supply 68 mA to each quadruple cell. A double bus would be required to pass twice the current. In addition, when one row contains green and blue light emitting elements, and one row contains red and white light emitting elements, the bus and interconnects can only power a single light emitting element row. The bus that supplies power to the green and blue light emitting elements must have a size to supply current up to 40 mA, and the bus that supplies power to the red and white light emitting elements. Would need to be sized to supply current up to 28mA. In this configuration, only the bus that supplies power to the green light emitting element and the blue light emitting element is considered, and the bus structure for these two light emitting elements supplies power to all four light emitting elements within the scope of the embodiment according to the present invention. Note that it is necessary to supply the same amount of current as the bus. Thus, according to this alternative embodiment of the present invention, the quadruple cell comprises a single pixel having four light emitting elements, the four light emitting elements comprising white light and light of three different colors. (Eg, red, green, blue) can be generated. In order to control such an OLED device, the present invention further controls the light emitting element to limit the current supplied to each set of four cells, so that the four light emitting elements can be specified at the same time. And a control device for preventing light from being generated.

  The present invention is preferably used in a quadruple cell forming a pixel group, but the quadruple cell may include a light emitting element including two or more pixels. The present invention can be used in both a bottom-emission type configuration and a top-emission type configuration. A plurality of buses and / or electrical interconnects can be formed between corresponding groups of quadruple cells. Having different groups of quadruple cells sharing buses and / or electrical interconnects can simplify layout and / or improve power distribution. For example, one set of quadruple cells can be connected to one bus and another set can have another bus.

  The present invention can be used in display devices. In a preferred embodiment, the present invention is used in flat-panel OLED devices consisting of small molecule OLEDs or polymer OLEDs. Such OLEDs are disclosed in, for example, U.S. Pat.No. 4,769,292 granted to Tang et al. On September 6, 1988, U.S. Pat.No. 5,061,569 granted to VanSlyke et al. On Oct. 29, 1991, etc. ing. Such devices can be manufactured using many combinations and variations of organic light emitting displays. These include both active-matrix and passive-matrix OLED displays with top-emission or bottom-emission configurations.

  Although this specification has primarily described in detail with respect to OLED displays, it will be appreciated that the same techniques can be applied to any active-matrix that generates light in response to current supplied to the light emitting elements of the display. In such devices, IR degradation can occur along the power line used to drive a plurality of such light emitting elements. For example, the present invention relates to an electroluminescent display device using a coatable inorganic material (such an inorganic material is described, for example, in Journal of Applied Physics, Vol. 83, No. 12, Jun. 15, 1998). Mattoussi et al. (In the article “Electroluminescence from heterostructures composed of poly (phenylene vinylene) and inorganic CdSe nanocrystals”) and other combinations of organic and inorganic materials that exhibit electroluminescence. The present invention can be applied to a display that can be driven by an active-matrix pixel driving circuit.

1 is a top view of an OLED device according to one embodiment of the present invention. FIG. FIG. 6 is a top view of an OLED device according to another embodiment of the present invention. 1 is a side view of a bottom-emission active-matrix OLED device proposed in the prior art. FIG. 1 is a top view of various active-matrix OLED device layouts known in the prior art. FIG. 1 is a top view of various active-matrix OLED device layouts known in the prior art. FIG. 1 is a top view of various active-matrix OLED device layouts known in the prior art. FIG. FIG. 6 is a top view of an OLED device according to another embodiment of the present invention. The performance of a conventional active-matrix OLED device is shown. The performance of a conventional active-matrix OLED device is shown. 1 is a top view of an OLED device according to an embodiment of the present invention having light emitting elements of four different colors. FIG. FIG. 4 is a top view of an OLED device according to another embodiment of the present invention in which light emitting elements of different four colors are grouped into sets of four, and the arrangement is different in the adjacent group. 4 is a flow chart of a color conversion algorithm that can be used in combination with the device of the present invention.

Explanation of symbols

1 Bright areas
2, 2a Dark area
4, 4a, 4b, 4c, 4d 4-cell set
8 space
10, 10a, 10b, 10c, 10d OLED elements
12, 12a, 12b Electrical interconnect
14, 14a, 14b bus
14 'additional bus area
16, 16a, 16b, 16c, 16d Connecting via
20, 20a, 20b, 20c, 20d Light emitting area
22 Connection
24, 24a, 24b, 24c, 24d electronic components
40 Insulator
42 Insulator
44R, 44G, 44B color filters
44K neutral filter
50 substrates
52 Transparent electrode
54 Organic layer
56 Reflective electrode
60, 61, 62 Colored light
63 Broadband light
78 Display
80 Green light emitting element
82 Red light emitting element
84 Blue light emitting device
86 White light emitting device
88, 88a, 88b Power line
90, 90a, 90b Electrical interconnect
92a, 92b selection line
94a, 94b capacitor wire
96a, 96b drive line
98 Beer
110, 114 4-cell cell with light-emitting elements in the first configuration
112, 116 Quad cell with light emitting element in second configuration
120 Inputting RGB signals
122 Converting to linear intensity
124 Steps to determine the minimum value
126 Step of subtracting part of the minimum value
128 Steps to calculate the white channel
130 Render steps

Claims (2)

A plurality of light-emitting elements laid out on a substrate (where each light-emitting element includes a first electrode, a second electrode, and one or more electroluminescent layers formed between these electrodes, and at least One electroluminescent layer emits light, at least one electrode is transparent, and the first electrode and the second electrode define one or more light emitting regions), and is formed on a substrate, An electronic component connected to the first electrode and / or the second electrode to drive one or more electroluminescent layers to generate light;
A plurality of buses connected to the light emitting elements and transmitting a common signal;
An active-matrix electroluminescent device comprising a plurality of electrical interconnects that intersect the plurality of buses and electrically connect the plurality of buses;
The plurality of light emitting elements are arranged as a plurality of groups of four light emitting elements, and each group includes four adjacent ones arranged around an intersection of the bus and the electrical interconnect. A quadruple cell is formed of light emitting elements, two light emitting elements of each quadruple cell are formed on each side of one bus, and four each on one side of one electrical interconnect. Two light emitting elements of a single cell are formed,
Each light emitting element of each quadruple cell has a bus or electrical separation that separates the light emitting elements of the quadruple cell from each other at a point closer to the intersection of the bus and the electrical interconnect than the edge of the quadruple cell. Connected to an interconnect, each quadruple cell shares a common bus or electrical interconnect with an adjacent quadruple cell, and adjacent 4 sharing a common bus the tuple cell, not separated by electrical interconnection to common, 4-tuple cells adjacent to share electrical interconnection to common are not separated by a common bus,
Emitting element of the four sets of cells on one side of a bus or electrical interconnects, on the other side of the bus or electrical interconnects, light emitting elements of the four sets of cells is inverted Chi di layout,
The plurality of buses and the plurality of electrical interconnects are formed in one common layer in one common step;
An active matrix device characterized by that .   The active matrix device of claim 1, wherein each quadruple cell comprises a single pixel having light emitting elements of four different colors.

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